This invention relates to the measurement of brain electrical activity.
There is a need for early detection of brain abnormalities. For example, in patients in whom brain tumors have been treated, it would be desirable to detect recurrence of tumor growth as early as possible. Conventional techniques for detecting recurrence (behavioral tests, CAT scans, and NMR studies) typically are unable to detect recurrence until substantial tumor growth has occurred.
Brain electrical activity mapping (BEAM) is a known diagnostic tool for detecting brain abnormalities. BEAM is described in U.S. Pat. No. 4,421,122; Duffy et al., "Brain electrical activity mapping (BEAM): A new method for extending the clinical utility of EEG and evoked potential data," Ann. Neurol., 5:309-321 (1979); Duffy, Bartels, et al., "Significance Probability mapping: An aid to the topographic analysis of brain electrical activity," Electroenceph. Clin. Neurophysiol., 512:455-462 (1981); Duffy, Topographic Mapping of Brain Electrical Activity, Butterworths (1986) (all incorporated by reference).